As he turned his sights toward Barack Obama last week, Mitt Romney attempted that most audacious form of political jujitsu: attacking your opponent over an issue on which you yourself are weak. For months, Romney has been hammered as an out-of-touch rich guy who lacks empathy for regular folks. (Romney has been his own worst enemy in this regard.) Now Romney is trying to neutralize the attack by turning it on Obama. On Tuesday, Romney argued that Obama lives in a bubble that disconnects him from real life:

“Years of flying around on Air Force One, surrounded by an adoring staff of true believers telling you what a great job you are doing, well, that might be enough to make you a little out of touch.”

Yesterday, Romney smacked Obama in Pennsylvania for having “spent too much time at Harvard.” Talking Points Memo’s Benjy Sarlin rounded up everything you need to know about this comically shameless line of attack from a man with two Harvard degrees.

But I suspect Romney won’t be shamed out of these zingers. He is happily taking advantage of two enduring political truths.

One is that, while the presidency offers countless political advantages, it does trap its occupant in a bubble of prestige and security that is impossible to avoid. The bubble is especially dangerous in hard economic times, when voters are on watch for politicians who may not be aware of their day-to-day hardships. The notion that George H.W. Bush hadn’t set foot in a supermarket in years was deadly (even if it was inaccurate). George W. Bush’s modest support collapsed for good at almost this precise moment in 2005; and even before then, Bush suffered steady criticism that he was insulated from bad news about the Iraq War. And God forbid the Commander in Chief should suffer some dignity-shredding humiliation like, say, a freak rabbit attack.

The second is that stereotypes die hard in politics, and certain attacks are more effective against one party than against the other. Romney may be even more of a Harvard man than Obama is. But he knows that Americans are probably more inclined to think of Democrats as the party of know-it-all academic elites. (It helps that Obama was actually a professor.) In fact, antielitism has been a crucial GOP line of attack in every recent election; never mind that in each case the substantive difference was almost nonexistent. In 2000, Bush — Yale and Harvard man, son of a President — mocked Al Gore as a snooty elitist. Four years later, Bush’s team taunted Vietnam vet John Kerry as a windsurfing, snow-skiing dilettante (never mind that Air Force reservist Bush rode a $2,300 bike, among other things). John McCain, he of the multiple houses and a half-lifetime in the U.S. Senate, cast himself as Joe the Plumber’s champion against the celebrity Professor Obama.

As an incumbent Democrat, then, Obama faces a kind of double jeopardy. The good news for him, however, is that in a megamillionaire political scion like Romney, he faces one of the most obviously elite GOP candidates in memory. Bush had at least mastered a kind of impish, Southern-dude style that took the edge off his pedigree. Romney’s constant gaffes and unusual vocabulary constantly reinforce his gilded résumé. Moreover, Obama comes from more humble means than did Gore or Kerry. This is no phony affectation:

I went to law school and college with the help of scholarships; so did my wife. We were still paying off student loans nine years after we graduated. I bought my first car for about $900. It had a big hole in the floor that allowed you to see the road, so I knew my wife wasn’t marrying me for my money. We had credit-card debt we hadn’t paid off. [In fact] our personal finances … weren’t stable until fairly recently.

Romney doesn’t really have an effective equivalent to that riff. But politics, unfortunately, often rewards the quality of an attack more than the truth underlying it. So don’t expect Romney to drop this tactic anytime soon.